lack

Compared meaning: not having enough of something (noun).

比较义项：缺乏、不足（名词）。

• want

  Formal or literary; now mainly survives in set phrases like 'for want of' or 'in want of', rarely used alone as a noun in everyday speech.

  正式或文学化用法；现在主要保留在固定搭配中，如“for want of”（因缺乏……）或“in want of”（缺……的），日常口语中很少单独作名词使用。

  The old cottage was clearly in want of repair after years of neglect.

  这栋老农舍多年疏于打理，显然亟需修缮。

• lack 本词

  The plain, everyday word for not having enough of something; used freely in almost any spoken or written context.

  最普通、最常用的词，表示某物不够或没有；几乎可用于任何口语或书面语境。

  There's a lack of parking spaces near the new office building.

  新建的办公楼附近停车位不足。

• deficiency

  More formal and technical; typically describes a specific, measurable shortfall, especially in health, nutrition or quality standards.

  更为正式和专业；通常指具体、可衡量的不足，尤其用于健康、营养或质量标准方面。

  Untreated iron deficiency can leave you feeling tired and weak.

  如果不加以治疗，缺铁会让你感到疲惫无力。

Want, lack, and deficiency can mean not having enough of something. Want is formal, mostly seen in phrases like 'for want of'. Lack is the plain, everyday word, used freely in speech. Deficiency is more formal and technical, describing a shortfall in health or nutrition.

这三个词都可表示“缺乏、不足”，但语体和搭配不同：lack 最常见、最中性；want 作此义时较正式或文学化，常见于固定搭配，如for want of（因缺乏……）、in want of（缺……的）；deficiency 更正式、专业，常用于医学、营养或质量标准语境，强调达不到应有的量。这里不比较want作动词“想要”的义项。